We give an introductory survey on the universal Vassiliev invariant called theperturbative series expansion of the Chern–Simons theory of links in euclidean space,
and on its relation with the Kontsevich integral. We also prove an original geometric
property of the anomaly of Bott, Taubes, Altschuler, Freidel and D Thurston, that
allowed Poirier to prove that the Chern–Simons series and the Kontsevich integral
coincide up to degree 6.